[RFI] QTH.COM Ad -- Need Help: ham antennas a...
k8ri at rogerhalstead.com
Sat Mar 14 18:35:37 PDT 2009
> I have copied this to the RFI list in case the more-expert folks there
> have some better suggestions for you ...
> If 2M FM is all that you intend to listen to then you are OK only
> using that to test but I recommend greater due diligence prior to
> The radio in your car probably has AM-BC, you can drive near to the
> lines with it - the HV lines here are quiet but the regular lines in the
> neighborhood for miles often blanket weaker AM signals - I suspect
> leaky cable-tv lines.
Cable leakage is easily identified by listening on 145.25 which I
believe is the audio subcarrier for channel 18. What it'll sound like
after they go digital? I don't know. One thing I do know. If the signal
is S9 a 5W HT will completely block the entire cable from that point on.
OTOH a 50 watt mobile? When I lived in Alma MI, they had some bad
leaks. I drove over to the cable company's headquarters which was where
they also had their distribution amps. I first demonstrated the HT at
100 mw in the office, then took it to 5W. They really weren't concerned
as the engineer said it was due to me being so close, so I asked him to
check while I went out in the parking lot almost a 100 yards away and
tested with the mobile rig. I keyed up and before I'd finished my call
he was standing on the steps waving his arms. Me transmitting there was
shutting down their entire cable system for the whole town and nearby area.
When I came home the next day I noted no signals on 145.25 coming in
along the main road although I did find some on side streets. The next
day I could find no leaks.
> The voltage of the lines isn't that important other than the HV lines
> are higher in the air and rarely radiate enough energy to get to the
> ground - you are unlikely to notice them unless you run a long (e.g.
> 160 or 80M) dipole up high and parallel to the lines.
I have one of the big transmission lines passing within about a quarter
mile. I've never heard it on any band. I have heard the local
distribution line a number of times, but the worst is an electric fence
about a half mile away. Fortunately that rarely bothers. OTOH I have
picked up "at times" a noise that pretty much blanks out 6-meters and
down through 20. It tapers off some where between 20 and 40. I've
never been able to track it down as about the time it looks like I'm
getting some where it quits.
> A good friend and broadcast TV engineer lives with HV lines across
> the back of his city lot and other lines nearby - he works HF & VHF
> all the time and has little noise. He has dipoles and wires and verticals.
As for HF I have 40 and 75 meter, half wave, center fed slopers close to
the power lines out front with the 75 meter antenna ending within about
30' of the right of way. Nary a peep.
>> David, I don't know the voltage of the power lines, but I can check
>> with the township or power company. I do have a 2 meter FM HT that I
>> could use. If there is noise, what can be done to eliminate it.
>> >>>Callsign: K3SRO
> >>> I am looking at a home that is located about 2 blocks from high
As I said above I have one of those big transmission lines passing about
a quarter mile or a tad less from me. That is about two of the local
city blocks. I've never heard them on any band 160 through 440. OTOH
that is no guarantee for any where else.
73 and good luck,
> >>> power lines on towers. How will this effect my reception on the HF,
> >>> UHF and VHF bands? Will I experience any power line noise or
> >>> interference while receiving or transmitting? Is there a way to check
> >>> for any power line noise before signing the agreement of sale?
> >>> Please contact Bob, K3SRO.
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